Tri-hybrid yoke

ABSTRACT

A tri-hybrid yoke including a center ring connected to a CF fitting connected to flexure arms. An inboard centrifugal force bearing assembly connects to the CF fitting and a grip. An outboard shear bearing assembly connects to the flexure arm and the grip. In use, the center ring and the CF fittings carry the centrifugal force at a position inboard of the flexure arm.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is related to U.S. Patent ApplicationPublication US 2019/0233095 A1, entitled Hybrid Yoke, which isincorporated herein by reference in its entirety.

BACKGROUND

This section provides background information to facilitate a betterunderstanding of the various aspects of the disclosure. It should beunderstood that the statements in this section of this document are tobe read in this light, and not as admissions of prior art.

Rotor systems of rotorcraft and tiltrotor aircraft include inboard andoutboard bearing assemblies that connect rotor blades to a yoke. Theyoke is connected by a hub to a drive mast driven by a power source. Theyoke is often manufactured of composite material instead of metal forweight savings. The inboard and outboard bearing assemblies accommodateforces acting on the rotor blades allowing each rotor blade to flex withrespect to the yoke/mast and other rotor blades. A particular distancebetween the inboard and outboard bearing assemblies is dependent onaircraft configuration where each configuration has an optimal distancefor that particular aircraft's loads and dynamics. Typically, theoutboard bearing assembly includes a centrifugal force (“CF”) bearingand a shear bearing connected to both the rotor blade and a tip of ayoke arm while the inboard bearing assembly includes a shear bearingconnected to both the rotor blade and the yoke in a cut-out proximatethe drive mast. CF loads can be significantly greater than shear loads.The CF bearing which accommodates the CF load is typically outboard atthe tip of the yoke arm since the cut-out in the yoke compromises thestrength of the yoke and provides a common yoke failure point.

SUMMARY

An example of a tri-hybrid yoke for a rotorcraft includes a center ringconnected to a centrifugal force (“CF”) fitting at a first CF joint, aflexure arm connected to the CF fitting, a second CF joint positionedwithin the CF fitting proximate the center ring and inboard of theflexure arm, and the center ring, the first CF joint, the CF fitting,and the second CF joint carry a CF load upon rotation of the tri-hybridyoke.

An example of a rotor blade assembly of a rotorcraft includes a centerring including a central aperture, a drive shaft connected to the centerring at the central aperture, a centrifugal force (“CF”) fitting to thecenter ring at a CF joint, a flexure attached to the CF fitting oppositethe center ring, a CF bearing connected to the CF fitting, a rotor bladeconnected to the CF bearing, an outboard shear bearing connected to theflexure and the rotor blade, and a CF load path of the rotor bladeassembly through the CF bearing, the CF fitting, the CF joint, and thecenter ring.

An example of a tri-hybrid yoke for a rotorcraft includes a center ringconnected to a centrifugal force (“CF”) fitting, a flexure arm connectedto the CF fitting, a cut-out in the CF fitting, inboard of the flexurearm, including a CF pocket, a first curved surface formed in the CFpocket, an inboard beam including a shaft extending from a bridge and asecond curved surface in the bridge opposite the shaft, a CF bearingheld by and between the first curved surface and the second curvedsurface, and the CF bearing is axially centered within the first curvedsurface and the second curved surface when the CF bearing is undercompression by a CF load.

This summary is provided to introduce a selection of concepts that arefurther described below in the detailed description. This summary is notintended to identify key or essential features of the claimed subjectmatter, nor is it intended to be used as an aid in limiting the scope ofclaimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with standard practice in the industry, variousfeatures are not drawn to scale. In fact, the dimensions of variousfeatures may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a perspective view of a tiltrotor aircraft in a flight readyposition according to aspects of the disclosure.

FIG. 2 is a perspective view of a tiltrotor aircraft in a stowedposition according to aspects of the disclosure.

FIG. 3A is a perspective view of a tri-hybrid yoke according to one ormore aspects of the disclosure.

FIG. 3B is an exploded perspective view of a tri-hybrid yoke accordingto one or more aspects of the disclosure.

FIG. 4 is a partial sectional view of a tri-hybrid yoke and inboardbearing assembly according to one or more aspects of the disclosuretaken along line 4-4 of FIG. 3A.

FIG. 5 is a schematic of a rotor blade connected to a tri-hybrid yokeaccording to one or more aspects of the disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof various embodiments. Specific examples of components and arrangementsare described below to simplify the disclosure. These are, of course,merely examples and are not intended to be limiting. In addition, thedisclosure may repeat reference numerals and/or letters in the variousexamples. This repetition is for the purpose of simplicity and clarityand does not in itself dictate a relationship between the variousembodiments and/or configurations discussed.

Referring to FIGS. 1 and 2, an illustrative tiltrotor aircraft 100 isshown. Tiltrotor aircraft 100 includes fuselage 102, landing gear 104,tail member 106, wing 108, wing tip 110, wing tip 112, rotor system 114,and rotor system 116. Rotor system 114 is connected to nacelle 115located on an end portion of wing 108 proximate wing tip 110, whilerotor system 116 is connected to nacelle 117 located on an opposite endportion of wing 108 proximate wing tip 112. Wing tip 110 is pivotable ata location on wing 108 outboard of nacelle 115. Wing tip 112 ispivotable at a location on wing 108 outboard of nacelle 117. Nacelles115 and 117 are pivotable between a helicopter mode where the rotorsystems are generally vertical and an airplane mode where the rotorsystems are generally horizontal. Nacelle 115 and nacelle 117 aresubstantially symmetric of each other about fuselage 102. Rotor system114 includes a plurality of foldable rotor blades 118. Rotor system 116includes a plurality of foldable rotor blades 120. Rotor blades 118 and120 may rotate in opposite directions to cancel the torque associatedwith the operation of each rotor system 114 and 116. The angle of thepivotable nacelles 115 and 117 relative to the wing, as well as thepitch of rotor blades 118 and 120, can be adjusted in order toselectively control direction, thrust, and lift of tiltrotor aircraft100. Further, rotor systems 114 and 116 are illustrated in the contextof tiltrotor aircraft 100; however, a singular rotor system withfoldable or non-foldable rotor blades can be implemented on othernon-tilting rotor and helicopter rotor systems. It should also beappreciated that teachings from tiltrotor aircraft 100 may apply toother aircraft such as airplanes and unmanned aircraft which wouldbenefit from folding rotor blades.

Fuselage 102 represents the body of tiltrotor aircraft 100 and may becoupled to rotor systems 114 and 116 such that the rotor systems withrotor blades 118 and 120 may move tiltrotor aircraft 100 through theair. Landing gear 104 supports tiltrotor aircraft 100 when tiltrotoraircraft 100 is landing or when tiltrotor aircraft 100 is at rest on theground. Vertical axis 122 is generally perpendicular to the longitudinalaxis of the wing and is generally positioned at the intersection of thefuselage and the wing. FIG. 1 represents tiltrotor aircraft 100 inoperational flying position in an airplane mode. FIG. 2 representstiltrotor aircraft 100 in a stowed position where rotor blades 118 havebeen folded generally parallel with each other and rotor blades 120 havebeen folded generally parallel with each other in order to reduce theprofile of the aircraft. In the stowed position, wing 108 is swivelledapproximately 90° to generally align with fuselage 102.

Generally each rotor system includes a drive mast driven by a powersource. A rotor system includes a yoke indirectly connected to the drivemast with a hub assembly and rotor blades indirectly connected to theyoke with inboard and outboard bearing assemblies. The bearingassemblies accommodate forces acting on the rotor blades allowing eachrotor blade to flex with respect to the yoke/mast and other rotorblades. The weight of the rotor blades and the lift of rotor blades mayresult in transverse forces on the yoke and other components. Examplesof transverse forces may include forces resulting from leading, lagging,and coning of the rotor blades. Leading and lagging generally refers tothe movement of a rotor blade in the plane of rotation. Coning generallyrefers to the upward and downward flexing of a rotor blade out of theplane of rotation due to lift forces acting on the rotor blade. Therotor blades may be subject to other forces, such as axial andfeathering forces. Axial forces generally refer to the centrifugal forceon the rotor blades during rotation of the rotor blades. Featheringforces generally refer to forces resulting from twisting motions thatcause a rotor blade to change pitch. The power source, drive mast, andyoke are components for transmitting torque. The power source mayinclude a variety of components including an engine, a transmission, anddifferentials. In operation, the drive mast receives torque from thepower source and rotates the hub and yoke. Rotation of the yoke causesthe rotor blades to rotate with the drive mast and yoke.

Referring to FIGS. 3A and 3B, tri-hybrid yoke 300 is shown. Each rotorsystem 114, 116 includes a separate tri-hybrid yoke. Tri-hybrid yoke 300includes a composite center ring, metal centrifugal force (“CF”)fittings attached to the center ring, and composite flexure armsattached to the CF fittings. The “tri-hybrid” combination provides theweight savings of composite material for the center ring combined withthe strength of metal for the CF fittings with the flexibility ofcomposite for the flexure arms. It should be understood that differentmetal and composite combinations for the center ring, CF fittings, andthe flexure arms may be possible. In the interest of clarity, a singletri-hybrid yoke is described herein with the understanding thattiltrotor aircraft 100 includes a pair of similarly configuredtri-hybrid yokes.

Tri-hybrid yoke 300 includes center ring 302, a plurality of CF fittings304, and a plurality of flexure arms 306. For weight saving purposes,center ring 302 is manufactured of a stiff, fiber-reinforced, polymeric,composite material. For strength purposes, CF fitting 304 is metal andmay be manufactured of, for example, aluminum, steel, or titanium.

Each flexure arm 306 is manufactured of a flexible composite material.For flexibility, each flexure arm 306 may be, for example, a compositepart constructed from reinforcement material, such as fiberglasssuspended in epoxy resin or a rubber compound. Reinforcement materialwithin flexure arm 306 can be oriented to customize how flexure arm 306responds to certain loads. For example, fiber reinforcement material canbe provided at various angles to customize the stiffness of flexure arm306 in different directions. Reinforcement material can be arrangedwithin flexure arm 306 such that it is stiff axially and laterally toresist centrifugal and lead/lag forces, however flexible vertically in adirection generally parallel with the drive mast to permit coning.Actual flexibility values provided by the constituent materials andarrangement of reinforcement layers are dependent on a particularaircraft's loads and dynamics.

Each CF fitting 304 is connected to center ring 302 such that CF fitting304 extends radially from central aperture 310. Each CF fitting 304 isgenerally equally spaced from each other around central aperture 310.Each CF fitting 304 connects to a flexure arm 306. A rotor blade isconnected to each CF fitting 304 and flexure arm 306 via inboard andoutboard bearing assemblies. For example, in the three rotor bladeconfiguration shown in rotor systems 114 and 116, 120° separates each CFfitting/flexure arm combination and thus each rotor blade. It shouldalso be appreciated that teachings regarding tri-hybrid yoke 300 canapply to rotor systems having greater or fewer rotor blades. It shouldalso be appreciated that teachings regarding tri-hybrid yoke 300 canapply to folding and non-folding rotor systems.

Tri-hybrid yoke 300 is connected to drive mast 312 through centralaperture 310 via a hub spring assembly and constant velocity joint.Center ring 302 includes mounting holes 314 in tab 316. Mounting holes314 and tab 316 are used to connect CF fitting 304 to center ring 302.

CF fitting 304 includes weight pockets 318. Weight pockets 318 reducethe overall weight of tri-hybrid yoke 300 without comprising thestrength of CF fitting 304. CF fitting includes mounting holes 320. CFfitting includes tangs 324, 325. Tangs 324, 325 define slot 326 betweenthem. Slot 326 is sized to engage tab 316. Tab 316 is engaged with slot326 and mounting holes 320 are axially aligned with mounting holes 314.CF bolts 322 seated within bushings 321 in mounting holes 314 and 320connect CF fitting 304 to center ring 302. Tangs 324, 325 provide adouble shear connection to center ring 302. Alternatively, center ring302 may be a bilateral ring including vertically aligned tangs sized toengage a single tab of the CF fitting to provide the double shearconnection.

CF fitting includes tangs 328, 329. Tangs 328, 329 define space 332between them. Space 332 is sized to engage flexure arm 306. Tangs 328,329 provide a double shear connection to flexure arm 306. Alternatively,flexure arm 306 may include a set of tangs sized to engage a single tangto provide the double shear connection. Each CF fitting 304 includesmounting holes 334. Mounting holes 334 are used to connect CF fitting304 to flexure arm 306. The connection between CF fitting 304 andflexure arm 306 does not carry any CF load. Clamp plates 336, 337 aremounted to CF fitting 304 proximate center ring 302. Clamp plates 336,337 are adjacent to and hold a shear bearing of inboard bearing assembly340. Each flexure arm 306 includes mounting holes 338. Mounting holes338 are used to connect flexure arm 306 to outboard bearing assembly348.

Each CF fitting 304 includes cut-out 342. Cut-out 342 extends fromproximate central aperture 310 to tangs 328, 329. Cut-out 342 is sizedto allow inboard bearing assembly 340 to fit within cut-out 342. CFpocket 344 is integrally formed with CF fitting 304. CF pocket 344 is aunitary portion of the CF fitting that has a curved surface forming aconical cavity. Each rotor blade connected to CF fitting 304 and flexurearm 306 shares central longitudinal axis 346 with CF fitting 304 andflexure arm 306. The central longitudinal axis of a rotor blade may alsobe referred to as a blade pitch change axis.

Referring to FIG. 4, inboard bearing assembly 340 is shown connected totri-hybrid yoke 300. Inboard bearing assembly 340 includes inboard beam402, CF bearing 404, and shear bearing 406. The CF and shear bearingsare generally elastomeric bearings constructed from a rubber typematerial that absorb vibration and provide for limited movement of therotor blades relative to the hybrid yoke and drive mast.

Inboard beam 402 includes bridge 410. Tangs 412, 414 are verticallyaligned and extend from bridge 410. Tangs 412, 414 include mountingholes 416, 417. Mounting holes 416, 417 are used to connect grip 502(FIG. 5) to inboard beam 402. As further discussed below, grip 502 isalso connected to an outboard beam which is mounted to flexure arm 306.Tangs 412, 414 include CF mounting hole 420. CF bolt 422 is sized toengage CF bushing 421 seated within CF mounting hole 420 and is used toconnect the grip to inboard beam 402. CF bolts 422, CF bushings 421, andCF mounting holes 420 are axially aligned in between tangs 412, 414.Inboard beam 402 includes shaft 424 extending from bridge 410 towardcentral aperture 310. Shear bearing 406 is attached to shaft 424, forexample by vulcanization or adhesive. Clamp plates 336, 337 and shaft424 hold or constrain shear bearing 406. Inboard beam includes cavity426 concentrically aligned with shaft 424. Cavity 426 is conical orparabolic shaped and positioned on bridge 410 opposite of shaft 424. CFpocket 344 includes cavity 428. Cavity 428 is conical or parabolicshaped and includes slot 430. Inboard beam 402 is connected to CFfitting 304 via CF bearing 404. CF bearing 404 is held by and betweenthe curved surfaces of cavity 426 and cavity 428. The curved surfaces ofcavity 426 and cavity 428 tend to axially center CF bearing 404 withinthe cavities when CF bearing 404 is under compression from CF loads. Itshould be understood that, an axially centered CF bearing is when thecentral longitudinal axis of the CF bearing generally intersects thecenter points of the curved surfaces of cavity 428 and cavity 426. CFbearing 404 includes tab 440. Tab 440 is sized to engage slot 430. Theengagement of tab 440 with slot 430 prevents rotation of CF bearing 404with respect to CF fitting 304. As an alternative, CF fitting 304 may bereplaced with a clevis that extends from CF bearing 404 for connectionto tangs 328, 329 to provide the anti-rotation functionality. Outboardbearing assembly 348 includes spindle 450 attached to flexure arm 306.Spindle bearing 452 is mounted to spindle 450 and outboard beam 454holds spindle bearing 452.

Referring to FIG. 5, a schematic of a rotor blade assembly including arotor blade connected to tri-hybrid yoke 300 is shown. CF fitting 304 isconnected to center ring 302 with CF bolts 322. CF joint 503 connects CFfitting 304 to center ring 302 with CF bolt 322 and CF bushing 321.Inboard beam 402 of inboard bearing assembly 340 extends through cut-out342 in CF fitting 304 and is connected to grip 502. CF joints 504, 505connect grip 502 to inboard beam 402 with CF bolt 422 and CF bushing421. CF bolts 422 within CF bushings 421 and CF mounting holes 420 aremanufactured to higher tolerances than the mounting hardware used inmounting holes 416, 417 that also connect inboard beam 402 to grip 502.As a result, at CF joints 504, 505 only CF bolts 422 or CF bushings 421carry the CF load from grip 502 through to inboard beam 402. Themounting hardware used in mounting holes 416, 417 that also connectinboard beam 402 to grip 502 do not carry CF load. CF joints 504, 505are positioned within cut-out 342 of CF fitting 304 and inboard offlexure arm 306. Outboard bearing assembly 348 connects flexure arm 306to grip 502 and blade tangs 508, 510 of rotor blade 506. Alternatively,grip 502 is not present and rotor blade 506 extends to inboard bearingassembly 340 where CF joints 504, 505 connect blade tangs 508, 510 toinboard beam 402 while rotor blade 506 connects to outboard bearingassembly 348 outboard of blade tangs 508, 510.

Outboard bearing assembly 348 includes a shear bearing. The connectionbetween flexure arm 306 and outboard bearing assembly 348 does not carryany CF load. The CF load path of rotor blade 506 is from blade tangs508, 510 to grip 502; through CF bolts 422 or CF bushings 421 of CFjoints 504, 505; to inboard beam 402; through CF bearing 404 to CFfitting 304; and through CF bolts 322 or CF bushings 321 of CF joint 503to center ring 302. Alternatively, in the absence of the grip, the CFload path of rotor blade 506 is from blade tangs 508, 510; through CFbolts 422 or CF bushings 421 of CF joints 504, 505 to inboard beam 402;through CF bearing 404 to CF fitting 304; and through CF bolts 322 or CFbushings 321 of CF joint 503 to center ring 302. The connection of grip502 or rotor blade 506 to tangs 412, 414 of inboard beam 402 provides adouble shear condition. The double shear condition prevents anyrotational moment about the connection of the grip or rotor blade to theinboard beam at each CF bolt 422 created by centrifugal forces acting onthe rotor blade during blade assembly rotation. The metal material of CFfitting 304 provides greater strength than a yoke manufactured entirelyof composite material. The stronger tri-hybrid yoke 300 is capable ofwithstanding the CF loads via an inboard bearing assembly.

The term “substantially” is defined as largely but not necessarilywholly what is specified (and includes what is specified; e.g.,substantially 90 degrees includes 90 degrees and substantially parallelincludes parallel), as understood by a person of ordinary skill in theart. In any disclosed embodiment, the terms “substantially,”“approximately,” “generally,” and “about” may be substituted with“within [a percentage] of” what is specified, as understood by a personof ordinary skill in the art.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the disclosure.Those skilled in the art should appreciate that they may readily use thedisclosure as a basis for designing or modifying other processes andstructures for carrying out the same purposes and/or achieving the sameadvantages of the embodiments introduced herein. Those skilled in theart should also realize that such equivalent constructions do not departfrom the spirit and scope of the disclosure, and that they may makevarious changes, substitutions and alterations herein without departingfrom the spirit and scope of the disclosure. The scope of the inventionshould be determined only by the language of the claims that follow. Theterm “comprising” within the claims is intended to mean “including atleast” such that the recited listing of elements in a claim are an opengroup. The terms “a,” “an” and other singular terms are intended toinclude the plural forms thereof unless specifically excluded.

What is claimed is:
 1. A tri-hybrid yoke for a rotorcraft, comprising: acenter ring connected to a centrifugal force (“CF”) fitting at a firstCF joint, the first CF joint comprising a double shear connection; aflexure arm connected to the CF fitting, wherein the CF fitting isconstructed of a different material from the center ring and the flexurearm; a second CF joint positioned within the CF fitting proximate thecenter ring and inboard of the flexure arm; an inboard beam including afirst tang and a second tang extending from a bridge, where the firsttang is vertically aligned with the second tang; a shaft extending fromthe bridge toward the center ring; a cavity in the bridge opposite theshaft; a CF bearing held by and between the cavity and the CF fitting; aclamp plate attached to the CF fitting; an inboard shear bearingattached to the shaft and held by the clamp plate; and an outboardbearing assembly connected to the flexure arm, wherein the tri-hybridyoke is configured to connect to a rotor blade at the second CF jointand the outboard bearing assembly whereby in use a CF load path of thetri-hybrid yoke is through the center ring, the first CF joint, the CFfitting, and the second CF joint, wherein the CF load path does notinclude the flexure arm or the outboard bearing assembly or a grip. 2.The tri-hybrid yoke of claim 1, further comprising: a cut-out in the CFfitting; and a CF pocket, where the CF pocket is a unitary portion ofthe CF fitting within the cut-out.
 3. The tri-hybrid yoke of claim 1,further comprising: a CF pocket, formed by the CF fitting, including afirst conical cavity; and the CF bearing held by and between the firstconical cavity and the cavity, wherein the CF bearing is axiallycentered within the first conical cavity and the cavity.
 4. Thetri-hybrid yoke of claim 3, further comprising: a tab extending from theCF bearing engaged with a slot in the first conical cavity.
 5. Thetri-hybrid yoke of claim 1, wherein the CF fitting further comprises: acut-out proximate the center ring; a CF pocket formed by the cut-out;and a weight pocket.
 6. The tri-hybrid yoke of claim 1, wherein the CFfitting is constructed of a metal.
 7. The tri-hybrid yoke of claim 1,wherein the flexure arm is connected to the CF fitting by a double shearconnection.
 8. The tri-hybrid yoke of claim 1, wherein the CF fitting isconstructed of a metal; and the flexure arm is connected to the CFfitting by a double shear connection.
 9. A rotor blade assembly of arotorcraft, comprising: a center ring including a central aperture; adrive shaft connected to the center ring at the central aperture; acentrifugal force (“CF”) fitting connected to the center ring at a CFjoint, the CF joint comprising a double shear connection; a flexureattached to the CF fitting opposite the center ring, wherein the CFfitting is constructed of a different material from the center ring andthe flexure; an inboard beam including a first tang and a second tangextending from a bridge, where the first tang is vertically aligned withthe second tang; a shaft extending from the bridge toward the centerring; a cavity in the bridge opposite the shaft; a CF bearing held byand between the cavity and the CF fitting; a clamp plate attached to theCF fitting; an inboard shear bearing attached to the shaft and held bythe clamp plate; a rotor blade connected to the CF bearing; an outboardbearing assembly comprising an outboard shear bearing, the outboardbearing assembly connected to the flexure and the rotor blade; and a CFload path of the rotor blade assembly through the CF bearing, the CFfitting, the CF joint, and the center ring, wherein the CF load pathdoes not include the flexure or the outboard bearing assembly or a gripconnected between the CF bearing and the rotor blade.
 10. The rotorblade assembly of claim 9, wherein the CF fitting further comprises acut-out proximate the center ring and the CF bearing is connected to theCF fitting in the cut-out.
 11. The rotor blade assembly of claim 9,further comprising a CF pocket formed by the CF fitting and including afirst curved surface.
 12. The rotor blade assembly of claim 9, furthercomprising: a CF pocket, formed by the CF fitting, including a firstconical cavity; and the CF bearing held by and between the first conicalcavity and the cavity, wherein the CF bearing is centered within thefirst conical cavity and the cavity when the CF bearing is undercompression by a CF load created by rotation of the rotor bladeassembly.
 13. The rotor blade assembly of claim 9, wherein the CFfitting further comprises: a cut-out proximate the center ring and theCF bearing extends through the cut-out; an CF pocket formed in thecut-out; and a weight pocket.
 14. The rotor blade assembly of claim 9,wherein the flexure is attached to the CF fitting by a double shearconnection.
 15. The rotor blade assembly of claim 9, wherein the CFfitting is constructed of a metal.
 16. The rotor blade assembly of claim9, wherein the flexure is attached to the CF fitting by a double shearconnection; and the CF fitting is constructed of a metal.
 17. Atri-hybrid yoke for a rotorcraft, comprising: a center ring connected toa centrifugal force (“CF”) fitting by a double shear connection; aflexure arm connected to the CF fitting, wherein the flexure arm isconstructed of a different material from the CF fitting; a cut-out inthe CF fitting, inboard of the flexure arm, including a CF pocket; afirst curved surface formed in the CF pocket; an inboard beam includinga shaft extending from a bridge and a second curved surface in thebridge opposite the shaft; a CF bearing held by and axially centeredbetween the first curved surface and the second curved surface; a shearbearing attached to the shaft and constrained by a clamp plate attachedto the CF fitting; and an outboard bearing assembly connected to theflexure arm, wherein the tri-hybrid yoke is configured to connect to arotor blade at the CF bearing and the outboard bearing assembly wherebyin use a CF load path of the tri-hybrid yoke is through the inboardbeam, the CF fitting, the center ring, and the CF bearing, wherein theCF load path does not include the flexure arm or the outboard bearingassembly or a grip.
 18. The tri-hybrid yoke of claim 17, furthercomprising a slot in the first curved surface and a tab extending fromthe CF bearing engaged with the slot.
 19. The tri-hybrid yoke of claim17, wherein the CF fitting is constructed of a metal.
 20. The tri-hybridyoke of claim 17, wherein the flexure arm is connected to the CF fittingby a double shear connection.